It is common place with weapons to mount various accessories to the barrel, receiver, stock, bow, handle or other portions of the weapon. Examples of such accessories are scopes, laser marker sights, night lights, night vision devices, ammunition holders, slings and bayonets. In the case of various sighting devices it is essential that they be rigidly mounted so that once the sight is aligned to correspond to the weapon boresight, the sight cannot move. Otherwise, the projectile fired from the weapon will not hit the target on which the sight is fixed. This is true of rifles, pistols, shotguns, bows, crossbows, launchers and other aimable weapons.
Some weapon manufacturers provide standard accessory mounting points as a part of their weapons. FIG. 1 is a simplified side view of a weapon, in this example, a rifle of the type sold by Heckler & Koch (hereafter abbreviated as H&K). H&K weapons are well known and distributed in the USA by the Heckler & Koch Company of Chantily, Va. and by numerous other licensees or representatives elsewhere in the world.
Referring to FIG. 1, weapon 10 comprises barrel 12, breech 14, loading and trigger assembly 16, fire rate selector 18, trigger 20, magazine 22, handgrip 24, shoulder stock 26, stock forepiece 28, charging slide 30, rear sight 32 and combined front sight and accessory mount 34 containing front sight post 36. Accessory mount 34 is rigidly attached to barrel 12.
Arrow 38 indicates the boresight of the weapon, that is, the path followed by the bullet. Laser target marker 40 is attached to accessory mount 34 in hole 44. Laser target marker 40, typically referred to as a laser sight, produces a small diameter intense light beam indicated by arrow 42 directed along the line of fire of the weapon. When light beam 42 intersects an object a bright spot is visible showing where the bullet will strike, provided that light beam 42 has been properly aligned with boresight 38. If laser sight 40 emits visible light, then the weapon user can usually see the light spot with the unaided eye. If the laser sight operates in the infra-red, then a night vision viewer is needed. Laser sights have the advantage compared to conventional iron or telescopic sights, that the shooter's peripheral vision is unobstructed and the light spot is easy to see under low light conditions.
It is highly desirable that laser sight 40 be rigidly mounted to weapon 10 so that handling and occasional bumps during use do not disturb the alignment between light beam 42 and weapon boresight 38. This is because the process of aligning beam 42 to boresight 38 is time consuming and may involve repeatedly firing the weapon under carefully controlled conditions, as for example from a firing bench. Alignment of the sight is often difficult or impossible under field conditions when the shooter may be dependent upon the correct sight-weapon alignment for his safety and survival. Even very small angular displacements of a laser sight can cause significant aiming errors. For example, an angular displacement of only 0.1 degree, causes an aiming error of 17 cm (about 7 inches) at a range of 100 meters. Thus, the assembly used to mount the laser sight or other alignment critical accessory to the weapon attachment point must be very robust, i.e., comparatively insensitive to bumps, knocks, vibration and shock.
It is desirable that the accessory be able to be easily and quickly removed and reinstalled on weapon 10 without any need for realignment or recalibration. For example, it may be necessary to remove a laser sight to change batteries or make other adjustments or to temporarily mount a different accessory. The sight holder should detach quickly and easily from the weapon without use of tools and when reattached to the weapon return the sight to the same relative position so that light beam 42 and boresight 38 are properly realigned.
It is also desirable that the holder be able to accommodate a variety of weapon accessories so that the same mounting assembly can serve multiple purposes. It is further desirable that the accessory mounting assembly not require any modification of the weapon, that is, it must attach to the weapon as it comes from the supplier without need for providing extra holes or grooves or other attachment points.
While prior art mounting assemblies permit various accessories (e.g., laser sights, flashlights) to be attached to weapons, such mounting assemblies have various deficiencies well known in the art. For example, they may allow an undesirable degree of relative movement of the accessory relative to the weapon boresight, or they may not return the accessory to a predetermined position after disassembly, or they may require special tools to change the accessory, or they may not be sufficiently robust to withstand bumps, knocks or repeated firing shock, or a combination of the above.
FIG. 2 shows an exploded view of standard H&K mount 34 equipped with a prior art laser sight 40. Accessory mount 34 is partially cut away in FIG. 2 to show cylindrical accessory mounting hole 44 therein. A front view of accessory mount 34 (i.e., looking along barrel 12 toward stock 26) is shown in FIG. 3. Laser sight 40 has lens 46 through which light beam 42 is emitted and cylindrical mounting plug 48 which mates with hole 44 in accessory mount 34. Plug 48 is retained in hole 44 by set screw 50 passing through existing side hole 52 in accessory mount 34. Holes 44 and 52 are standard holes provided by H&K in accessory mount 34.
There are differences in the size of holes 44 and 52 from weapon to weapon as a result of normal manufacturing variation. If plug 48 is to be able to fit weapons having the same nominal mounting hole size, some clearance amount must be provided between plug 48 and hole 44. Thus, plug 48 will be loose in some mounting holes and tight in others. This clearance amount permits angular displacement of plug 48 in mounting hole 44 and possible misalignment of the sight. Further, if plug 48 is anchored in hole 44 using a set screw passing through existing side hole 52, as shown for example in FIG. 3, plug 48 is off-center in hole 44 by clearance amount 54, and there is only limited contact area between outer surface 47 of plug 48 and inner surface 49 of hole 44. Thus, laser sights and other accessories mounted in this fashion are not as robust as is desired. Further, the small contact area between the set screw and hole 52 make it difficult to repeatably remount the accessory in a precisely determined position. Accordingly, a need continues to exist for improved accessory mounting means and methods for weapons.
The description herein refers to "weapons" and to "bullets" and illustrates the various concepts in terms of a firearm having a particular mounting hole arrangement. However, this is merely for convenience of explanation and not intended to be limiting, and as used herein, "weapon(s)" is intended to refer to any form of aimable weapon, including but no&: limited to firearms, air operated arms, bows, crossbows, grenade or missile launchers, rifles, pistols, shotguns, and so forth, and "bullet(s)" is intended to refer to any form of projectile, including but not limited to arrows, bolts, bullets, missiles, grenades, and so forth.